This invention relates generally to fiber optic connectors and, more particularly, to a fiber optic connector for coupling a pair of fiber optic cables or a single fiber optic cable and a light source or detector in a separable in-line connection.
It is generally known in the industry that a fiber optic cable generally includes an optical fiber surrounded by a coating or "jacket", with strength members extending longitudinally between the optical fiber and the outer coating or jacket. An optical "fiber" conventionally includes a core surrounded by a cladding, both of which normally are of glass but with different indexes of refraction. However, in the specification and claims herein the terms "core" or "fiber core" will be used to denote this composite element of the fiber optic cable.
The terminal end surface of an inner fiber core of a fiber optic cable for use in lightwave transmission must be flat and highly polished to minimize insertion losses. The inner fiber core typically must also be axially, laterally and angularly aligned within certain parameters to establish an excellent optical coupling between two fiber optic cables. The success achieved in the development and production of fiber optic cables has therefore focused strongly upon low loss connectors and couplers for such cables including in-line connectors. The ability to design, manufacture, deploy and service a data transmission line, for instance, requires suitable connectors in order to assure the continued progress of the fiber optics field. Accordingly, connectors for this and other applications must be developed which can be used without any significant increase in insertion losses.
Many fiber optic connectors presently available are precision, expensive instruments providing very low insertion losses, but they are designed for certain applications such as long distance applications in telephonic systems and in other applications requiring extremely low insertion losses where expensive low loss connectors may be employed. It has been found, however, that expensive low loss connectors are not always well suited for applications requiring a large number of connectors where very expensive connectors are not economically feasible. For instance, in such applications as computers, cable television and other data transmission applications, a large number of fiber optic cables are employed, and there is a need for low cost, low loss fiber optic connectors which minimize insertion losses due to off-centering of the fiber core relative to the outer dimensions of the connector or terminal member. It is well known in such applications to use low cost fiber optic cables in which the inner fiber core often is not concentric with the outer coating or cladding. Of course, this non-concentricity has a tendency to lead to excessive insertion losses when a connector that utilizes the outer coating or cladding as a jigging surface is put into a data transmission line.
As stated above, alignment of the fiber core is important to minimize insertion losses, but most connectors which are effective to properly position or center the core with respect to the mating terminal end of the connector or terminal member are very expensive instruments. Such connectors often employ bushings, centering rollers, internal sleeves and the like for properly positioning or centering the core. Some such connectors employ expensive manufacturing steps to apply epoxy within the connector to effect proper centering of the core.
This invention is directed to solving these problems by providing a new and improved fiber optic connector and means of centering or properly positioning optical fibers or inner fiber cores of fiber optic cables with respect to the mating end of the connector. The fiber optic connector of this invention also is directed to the problems of reducing manufacture and assembly costs as well as providing a connector which, when assembled, precludes axial movement of the fiber optic cable relative to the connector to insure that proper positioning of the fiber core is maintained during use.